<!DOCTYPE html>
<html class="reftest-wait">
<title>Update styles when iteration composition changed from replace to
accumulate</title>
<script src="animation-utils.js"></script>
<style>
#test {
  width: 100px; height: 100px;
  background: blue;
}
</style>
<div id="test"></div>
<script>
  var anim = document.getElementById("test")
    .animate({ marginLeft: [ "0px", "100px" ] },
             { duration: 100000,
               delay: -99999, // For starting right before second iteration.
               easing: "steps(1, start)",
               iterations: 2,
               iterationComposite: "replace" });

  waitForIterationChange(anim).then(() => {
    // Changing iterationComposite updates the element style.
    anim.effect.iterationComposite = "accumulate";
    requestAnimationFrame(() => {
      // Now margin-left of the element should be 200px.
      document.documentElement.classList.remove("reftest-wait");
    });
  });
</script>
